textproduct: Albany

WHAT HAS CHANGED

Refined timing for showers and thunderstorms Sunday. First, more widespread round moves through in the morning to early afternoon. Additional, scattered showers and thunderstorms develop from mid afternoon to early evening. Coverage looks less later in the day. There remains a Marginal Risk (level 1 of 5) of severe thunderstorms across the entire region on Sunday.

KEY MESSAGES

1) Likelihood of showers and thunderstorms increases late tonight into Sunday. A few storms may become severe on Sunday.

2) Isolated to scattered showers and thunderstorms are expected Monday and Tuesday, especially near and north of I-90. Temperatures will be below normal.

3) Chances of showers and thunderstorms return late next week along with warmer temperatures.

DISCUSSION

KEY MESSAGE 1...

An upper level trough over our region will deepen through the rest of the weekend, as a closed low develops across the Great Lakes and far SE Canada. Initially, our area will be on the downstream/diffluent side of the trough axis, with an associated occluded surface front tracking NE Sun morning into early afternoon. A weak surface wave developing along the front along with PWAT anomalies briefly increasing to +1 to +2 STDEV, could result in brief downpours associated with any convection with the occluded front. There is a Marginal Risk (level 1 of 5) of severe storms Sunday, first with convective clusters/lines in the morning to early afternoon with potential for isolated damaging winds gusts. Then, there looks to be another period for more cellular storm mode in the afternoon, with de-stabilization (SB CAPE of 700-1500 J/Kg) and 0-6 km shear increasing to 35-40 kt in wake of the front (from REFS). Breaks of sunshine and residual low level moisture, along with falling heights aloft will result in potential for some additional severe storms, with both isolated damaging wind gusts and large hail the main threats. Coverage of shower/T-storms should be less compared to the morning though.

Convection should dissipate shortly after sunset Sunday evening, as instability wanes and a small low level ridge builds in from the west.

KEY MESSAGE 2...

The main core of the upper level low mentioned above will be firmly established near the far southern Ontario/Quebec border by Mon and will be anomalously strong (500 mb height anomalies of -2 to -3 STDEV). A potent short wave disturbance rotating around the periphery of the low center, is expected to move across our area. This will result in additional showers and a few T-storms, especially Mon afternoon to early evening. Showers will be most numerous across the Adirondacks, where there will be upslope/lake enhancement with a cold core aloft moving overhead with W-SW flow developing. While the overall threat for severe weather appears low, there is potential for at least a few storms to produce small hail and/or gusty winds due to steepening low/mid level lapse rates.

The core of the upper low is expected to track into southern Quebec on Tue, with the system's upper trough axis still in place across our region. This will result in additional showers developing, although lower coverage compared to Mon (mainly isolated to scattered). Showers will be most favored across westerly upslope areas of the higher terrain. It will also be breezy, with westerly winds gusting 20-25 mph at times in favored areas. Temperatures will remain below normal through Tuesday.

KEY MESSAGE 3...

After a break in the unsettled weather on Wed, chances for showers/T-storms will increase again during the Thu/Fri time frame, as a broad upper level trough approaches from the west. Potential multiple short wave passages should result in scattered to numerous showers, with T-storms also possible depending on instability and moisture return. Confidence in timing/coverage is low due to uncertainty in details of smaller scale features this far out. Temperatures look to warm back to normal mid-late next week too.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

Through 18z/Sunday...VFR conditions remain through the afternoon across the terminals before ceilings begin to lower to MVFR this evening due to an approaching frontal system. MVFR ceilings will continue overnight at all of the terminals along with the possibility of fog/mist developing at KGFL and KPSF near sunrise. CAMs also suggest rain showers arriving between about 08z to 13z from the west lowering ceilings and visibilities to MVFR. After sunrise, model soundings continue to show low stratus persisting into the late morning maintaining MVFR ceilings and even lowering to IFR/LIFR for periods through the end of the TAF period. Additional chances of steadier rain showers and isolated thunderstorms through the end of the TAF period could lower flight conditions to MVFR/IFR, but confidence will increase with following TAF cycles. Winds through the TAF period will prevail out of the southeast with speeds this afternoon 5-10 kt becoming 5 kt or less overnight. Winds tomorrow generally range 5-10 kt, however stronger gusts around 25 kt could accompany any thunderstorms that develops.

Outlook...

Sunday Night: Low Operational Impact. Slight Chance of SHRA...FG. Monday: Moderate Operational Impact. Chance of SHRA...TSRA. Monday Night: No Operational Impact. NO SIG WX. Tuesday: Low Operational Impact. Breezy. Slight Chance of SHRA...TSRA. Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: No Operational Impact. NO SIG WX. Wednesday Night: No Operational Impact. NO SIG WX. Thursday: Moderate Operational Impact. Chance of SHRA...TSRA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.